Project Summary Glioblastoma (GBM) is the most common and aggressive primary brain tumor, which represents an enormous unmet need in current oncology. There is an urgent need for new molecular targets, concepts, and approaches to defeat this disease. MicroRNAs emerged in recent years as key regulators of gliomagenesis, as well as promising therapeutic targets and biomarkers for brain tumors. However, other classes of small non-coding RNA (sncRNA) with regulatory potential remain largely unexplored. Communication between GBM tumor cells and diverse normal cells of the brain microenvironment is one of the least investigated aspects of glioma biology. Recent studies indicate that GBM release massive amounts of extracellular RNA (exRNA), which may represent a means of communication between the tumor and its intracranial environment. Among various species of highly abundant exRNA, we identified poorly studied classes of sncRNA, including angiogenin- produced tRNA-derived fragments (tRF) and Y-RNA. Several functions (including regulation of translation and RNAi) have been assigned to the ribonuclease angiogenin (ANG) and its stable RNA products in normal and cancer cells, but their paracrine and autocrine functions in GBM and its microenvironment are unknown. Using state-of-the-art co-cultures of glioma with normal cells of the brain microenvironment (astrocytes, microglia, endothelial cells), we detected the uptake of glioma-derived sncRNAs by the normal cells of the brain. To investigate the functions of ANG-produced sncRNA in glioma, and elucidate the impact of their transfer to normal cells of the brain, in this exploratory project we will 1) characterize the repertoire of ANG-induced small RNA species expressed and released by GBM using deep RNA sequencing; 2) determine the effects of ANG and its most abundant RNA products on growth and drug response of glioma cells, and 3) validate the uptake and test the effects of specific ANG products on the phenotypes of normal recipient cells of the brain. Therefore, this project will examine the role of one of the most highly expressed, but poorly studied classes of sncRNA in glioma, in particular, and will likely have high relevance to other cancers in general. More broadly, it may discover novel and unanticipated regulatory RNA species, as well as RNA biomarkers for diagnostics and monitoring of disease.